P0605
Internal Control Module Read Only Memory (ROM) Error
Engine control module (ECM)
Generic OBD-II
High
What it means
P0605 means the engine control module has failed an internal self-test of its read-only memory (ROM) — the ECM's own program storage is reporting an error. Because the ECM runs the engine, this can cause stalling, a no-start, warning lights and erratic running. It usually points to the module itself, but check its power and grounds first.
High
Can I keep driving? Treat as serious — an internal ECM fault can cause stalling or a no-start without warning; get it diagnosed before relying on the car.
Common symptoms
What you'll notice
- Check-engine light on, often with other warning lights
- Stalling or a no-start
- Poor running or reduced power
- Erratic operation or gear-shift problems
Common causes
Most likely first
- Poor ECM power supply, ground or reference voltageLikely
- Corroded or loose ECM connectorsCommon
- Damaged wiring in the ECM circuitsCommon
- Corrupted ECM software needing a reflashLess often
- Internally failed ECMLess often
How to diagnose & fix
Work through it in order
- Check the battery, ECM power feeds and ground connections — a weak supply is the cheapest and most common trigger.
- Inspect the ECM connectors and harness for corrosion, looseness or damage.
- Clear the code and see whether it returns after a solid supply is confirmed.
- Reflash or update the ECM software to the latest calibration per the manufacturer.
- Replace or professionally reprogram the ECM only if the internal ROM fault persists.
FAQ
Quick answers
Is it safe to drive with P0605?+
Not really. An internal ECM error can cause stalling or a sudden no-start, so avoid relying on the vehicle until it's diagnosed. Check power and grounds first — it isn't always a dead computer.
Can I just clear P0605?+
You can try, and if a poor power/ground connection set it the code may stay away once that's fixed. If it returns, the ECM needs a reflash or replacement.
Related codes
Often seen with P0605
Read & clear P0605 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX